38-10 -> 12: Match Drilling Canopy Frame Close out / Initial Prep for Canoopy Rail Parts

Drilling the Canopy Frame Close Out

With the canopy frame assembly upside down on some timbers and set so that there was as little twist as possible, the canopy frame close out skin was pulled over the side of the bench to initiate the curve. This gets some holes dimpled on the end flanges, where this needs to nest against the bottom of the side rail bases. As i mentioned in a previous post, in hindsight, i would have left the side rail bases un-countersunk, and not dimpled the close out at this point. The canopy close out skin was then cleco'd in position and twist in the canopy was checked. 

Initial check for twist with the canopy close out clecod in place was perfect!

I also backed it up using the winding sticks.

The first set of drilling, on 38-10 Step 8 was to drill from the outside of the skin #40 the holes between the skins and the side rail plates / substructure. Each hole was uncleco'd, drilled, then re-clecod. Then the assembly was checked for twist again.

Chekcing for twist after drilling the skin / side plates 

The drilling of the canopy close out was interesting - instead of drilling to #30 and #40 as usual, we underdrill to 3/32 and 1/8. The final drilling to size is done right before riveting. To make sure i drilled each hole the correct size, the drill size was marked in sharpie. After drilling each group of holes, the twist was checked once again before moving onto the next set of holes. A final check at the end showed the canopy rails were parrallel.

Drill sizes marked for "3" aka 3/32 or "8" aka 1.8

I followed the specific drill sequence.

The final check for twist was perfect.

Canopy Rail Parts - Initial Preperation

The canopy rails consist of a few parts, which are riveted together early on, before more countersinking and drilling operations are carried out later. I wanted all mating parts to have primer between them, so i completed a number of steps for the canopy rails, then primed everything, and went back and continued working on the rails. 

The first task is to work on the canopy rail angles - these rivet to the lower flat sections of the canopy frame (which are flat on the fuselage side rails), and also rivet to the canopy side rails themselves. They therefore need to be flat on the botttom, but bent inboard. This means they need some heavy fluting! The first step was to mark where the holes from the canopy side rails would land on the canopy rail angles - so we don't flute where a hole needs to be. I then fluted the rail angles and used the kitchen bench to make sure they were dead flat, and also aligned with the holes in the lower flat canopy rails.

Before!

After! - Much to the chagrin of the family, the kitchen bench was the flattest thing i could find to make sure the canopy rail angles were flat on the bottom.

All the world is a workbench.

Interestingly, the canopy rail angles are countersunk on the bottom. These are riveted with AN470 dome head rivets, so the dimples are for the shop heads to nest into, making the underside surface flush.

Here you can see how the rail angles needed some tweaking to fit. 

Once all this prep was done, all these parts were primed ready for riveting together.